Several applications are known in which electrical connections need to be provided underwater. Examples include a subsea installation for the production of hydrocarbons from a subsea well, in which different components of the subsea installation need to be connected electrically. Such connections may for example comprise a connection from a topside installation, such as a floating or fixed platform, or from an onshore site to a subsea component. Such connection can be provided by an umbilical or a subsea cable. Other connections include electrical connections between different types of subsea equipment, such as a connection between a subsea transformer and subsea switchgear, electrical connections to a pump or a compressor or the like.
For providing an underwater electrical connection, wet-mateable connectors are known which can be mated underwater. Although such type of connector is generally more complex than a corresponding dry-mate connector, which has to be mated above water, wet-mateable connectors have several advantages. Components of the subsea installation can for example be disconnected under water and can be retrieved for servicing or exchange, additional components may be connected to an existing subsea installation, a subsea installation can be connected electrically after installation thereof at the ocean floor, and the like.
A general problem with subsea connectors is the corrosive character of seawater. Seawater generally causes corrosion and degradation of materials exposed thereto. Exposed surfaces are furthermore prone to the growth of organic material thereon, such as algae, bacteria and the like. Such marine growth can be detrimental to the functioning of the subsea connector.
From the document GB 2 429 587 A, an electrical connector for underwater mating is known which has an isolation tube containing dielectric oil. A rear lip-seal seals onto the isolation tube. When the contactor is mated, the rear lip-seal moves along the surface of the isolation tube. Since the isolation tube is exposed to seawater, so that marine growth can occur, the sliding seal is vulnerable to wear and tear, and there may be the danger of a leakage after a certain number of mating/de-mating cycles.
Another possibility of protecting a part of a subsea connector is the providing of a so called “dummy plug” to which the connector part is mated when it is not in use, i.e. when it is unplugged. Components of the connector part, such as a pin can thus be protected effectively from the surrounding seawater. Such dummy plug generally needs to include all features of a standard plug at its connecting section, but does not connect to a cable but only to a dummy gland, which isolates the pin from the metal work and which may be used for electrical testing. As such dummy plug may need to be provided for each un-mated connector part, significant costs can be incurred.